No Customization in Navigation Submenus

Did you delete (or change the name of) the Contrast color in the theme? That is what is used for the background color of that submenu, and when checking our your site, it appears the var(--wp--preset--color--contrast) no longer exists. (Hence why the submenu is now transparent.)

I have not made any code additions or edits to the theme.

To my recollection, I have not changed the contrast color of the theme. It has always been the following and in previous version of Frost, the submenu followed the color of the navigation bar automatically:

Somewhere along the way something must have changed—you now have a color of Main, as seen in this CSS variable: var(–wp–preset–color–main).

Can you give me more to go on? I’ve tried to turn off all the plugins which is how I make changes to the code if I ever do and that did not work. Where or how would I have added a color of Main?

Out of the box, the screenshot below shows the Frost color scheme: Base, Contrast, Primary, Secondary, Neutral:

Looking at your CSS, it appears your color scheme has been customized (likely through Site Editor or theme.json) and is shown as this:

--wp--preset--color--primary: #24418f;
--wp--preset--color--secondary: #e4524e;
--wp--preset--color--tertiary: #ffefdb;
--wp--preset--color--main: #000000;
--wp--preset--color--base: #fff;

Thank you, Brian, that was very helpful. I was able to find the Navigation Block color options. Posting an image in case it helps anyone in the future.